The present invention relates generally to control systems for internal combustion engines, and more particularly, to an electronic throttle control system.
Many previously known motor vehicle throttle controls have a direct physical linkage between an accelerator pedal and the throttle body so that the throttle plate is pulled open by the accelerator cable as the driver depresses the pedal. The direct mechanical linkage includes biasing that defaults the linkage to a reduced operating position, in a manner consistent with engine operation. Nevertheless, such mechanisms are often simple and unable to offer optimal fuel consumption, emissions efficiency and performance to changing traveling conditions.
An alternative control for improving throttle control and the efficient introduction of fuel air mixtures into the engine cylinders is presented by electronic throttle controls. The electronic throttle control includes a throttle control unit that positions the throttle plate by an actuator controlled by a microprocessor based on the current operating state determined by sensors. The processors are often included as part of a powertrain electronic control that can adjust the fuel air intake and ignition in response to changing conditions of engine vehicle operation as well as operator control. Protection may be provided so that an electronic system does not misread or misdirect the control and so that unintended operation is avoided if portions of the electronic control system were to suffer a failure.
Typical electronic throttle control systems require the use of multiple controllers. This is done because existing microprocessor based powertrain control modules do not have the chronometric/performance capability to perform the additional function of electronic throttle control. Unfortunately, adding multiple controllers adds to overall system cost and complexity while reducing reliability.
The disadvantages associated with these conventional electronic throttle control techniques have made it apparent that a new technique for electronic throttle control is needed. The new technique should require only one additional controller for both powertrain and electronic throttle control. Additionally, the new technique should reduce overall system cost and complexity while improving reliability. The present invention is directed to these ends.
It is, therefore, an object of the invention to provide an improved and reliable electronic throttle control system. Another object of the invention is to require only one controller for both powertrain and electronic throttle control. An additional object of the invention is to reduce overall system cost and complexity while improving reliability.
In accordance with the objects of this invention, an electronic throttle control system is provided. In one embodiment of the invention, an electronic throttle control apparatus includes a powertrain control module having at least two microprocessors. The powertrain control module is coupled to controls an internal combustion engine and an electronic throttle. A main microprocessor is located in the powertrain control module that includes control logic operative to monitor and control the internal combustion engine and derive the desired throttle position. A secondary microprocessor is also located in the powertrain control module and is in communication with the main microprocessor. The secondary microprocessor controls throttle plate position, while interrogating the main microprocessor to verify correct execution of throttle control monitoring software in the main microprocessor. If a malfunction is detected, then the secondary microprocessor can disable the internal combustion engine by overriding the main microprocessor""s control of the engine.
The present invention thus achieves an improved electronic throttle control system. The present invention is advantageous in allows the use of only one controller for both powertrain control functions and electronic throttle control.
Additional advantages and features of the present invention will become apparent from the description that follows, and may be realized by means of the instrumentalities and combinations particularly pointed out in the appended claims, taken in conjunction with the accompanying drawings.